The exhaust system of an internal combustion engine of an automotive vehicle includes various component units such as an exhaust pipe, an exhaust-cleaning catalytic converter and a muffler or mufflers. These component units of the exhaust system are subjected to the vibrations originating in the power cylinders of the internal combustion engine and thus constitute a vibration system having a certain resonance frequency. When the frequencies of the vibrations transmitted to the exhaust system from the power cylinders of the engine happen to be coincident with the resonance frequency of the vibration system, the vibrations are carried to the vehicle body structure and produce booming noises in the passenger compartment of the vehicle.
In order to lessen such vibrations transmitted from the component units of the exhaust system to the passenger compartment, it has be proposed to use an exhaust unit support device constructed and arranged in such a manner as to dampen the vibrations of the exhaust component units. An example of such an exhaust unit support device is shown in Japanese Utility Mode Provisional Publication No. 52-90625. The prior-art exhaust unit support device therein shown includes a vibrating-damping mass member supporting a catalytic converter of the exhaust system and constitutes a vibration system in itself. The vibration-damping mass member included in the exhaust unit support device, however merely plays the role of a weight and is not adapted to support a unit constructed and arranged separately of the exhaust unit support device. For this reason, not only a disproportionately large number of component members and elements are required to construct the exhaust unit support device, but also extra steps are necessitated for the welding of the vibration-damping mass member to other members of the exhaust unit support device during installation of the exhaust system of the engine on the vehicle body structure. The present invention contemplates elimination of such a problem in a known exhaust unit support device of the described nature.